Activity-based resource allocation among virtual-computing sessions

ABSTRACT

A method of dynamically controlling use of a shared computing resource by a set of virtual-computing sessions of a client computing device includes state identification operations on per-virtual-channel event data to identify activity states of virtual channels of the sessions, performing a resource allocation operation on activity state data including (i) accumulating activity state data for all virtual channels of each session to produce per-session activity values, and (ii) using the per-session activity values to generate resource usage control signals representing a target pattern of use of the shared computing resource by the sessions based on their activity values. An enforcement operation uses the resource usage control signals to establish the target pattern of use of the shared resource of the sessions.

BACKGROUND

The present invention is related to the field of distributed computing,more particularly to distributed computing in which a client computingdevice interacts with a server computer via a set of virtual-computingsessions, such as employed for virtual desktops, virtualizedapplications, etc. Even more particularly, the invention is directed tothe allocation of physical resources, such as limited network bandwidth,in such distributed computing systems.

SUMMARY

Certain operating scenarios for computer systems can expose problemswith the way that physical computing resources are allocated. Aspects ofthis problem are briefly described, and an alternative approach that canaddress this problem is described in detail. The description focuses onnetwork bandwidth as a specific example resource, but those skilled inthe art will appreciate that it can be adapted to other resources suchas memory, CPU, etc.

A user connecting to a virtual-computing session (such as a remotedesktop type of session) from a challenged network connection with lowbandwidth may suffer poor performance. This could happen in scenarioslike the following:

1. Roaming user connecting from remote client locations or cafes etc.

2. Connecting from a country having weak network infrastructure. Forinstance, many ASEAN countries rely on satellite link for interstatecommunication. Another example is Australia, where MPLS links are veryrare.

Also, it is common that so-called “thin clients” are used as endpointsin system utilizing virtual-computing session techniques. A typical thinclient comes with minimal resources such as CPU, memory, etc. Optimalallocation of these resources can help in enhancing user experience.

Computer systems may try to optimize performance in various ways. In oneapproach, a client-side virtual-computing agent may optimize performanceof virtual channels of a session by assigning relative priority to thevirtual channels. This can improve performance within the scope ofsingle session.

Other approaches may use network-based devices or other client-side orserver-side mechanisms based on assigning priorities etc.

However, existing approaches may not address the relative priorities ofmultiple virtual-computing sessions running on a client device. Forinstance, there may be two applications launched by a user, with onebeing actively used and other performing background activity such as abackground browser window. In this case, if network bandwidth has beenallocated equally to the two sessions, there is inefficiency andperformance suffers, because the network bandwidth allocation has nottaken into account the differentiation between the active or foregroundapplication and the inactive or background application. This problemwill be aggravated when network bandwidth is limited and multiple remoteapplications are launched by a user which compete for network bandwidth.

An alternative approach for handling such scenarios, described herein,is to intelligently distribute the bandwidth and/or to selectivelythrottle the bandwidth. This involves identifying the activeapplication(s), discerning user intent, making dynamic resourceallocation decisions and implementing them by enforcement mechanisms.Additionally, the technique preferably adapts to administrative policiesand/or user environment.

Thus an approach described herein generally involves operations selectedfrom the following, carried out by components operating at a clientdevice and/or a server device or network device or a combination ofthese devices:

1. Measure the active application/applications requiring higherresources.

2. Monitor the user environment such as network bandwidth, CPUutilization, battery charge level, memory availability, GPU usage etc.

3. Perform predictive analysis based on application hooks, monitoringthe environment, user input, etc.

4. Tailor operation according to administrative policy

5. Adapt system operation to accommodate the dynamic resourceallocation, such as by increasing keep alive logic and expected delaysin packet processing

7. Throttle resource usage across sessions and/or applications.

8. Throttle resource usage within a session.

More particularly, a method is disclosed of dynamically controlling useof a shared computing resource by a set of virtual-computing sessions ofa client computing device, each session including a respective set ofvirtual channels for respective input/output functions of the session.

State identification operations are performed on per-virtual-channelevent data to identify respective activity states of the virtualchannels. The activity states include, for each virtual channel, a highactivity state and a low activity state, the high activity statecorresponding to active current use of the respective input/outputfunction, the low activity state corresponding to current non-use of therespective input/output function. The activity states are represented bycorresponding activity state data.

A resource allocation operation is performed using the activity statedata (current data combined with the algorithm from historical data).This operation includes (i) accumulating, for each session, activitystate data for all virtual channels of the session to produce arespective per-session activity value, and (ii) using the per-sessionactivity values for the sessions to generate respective resource usagecontrol signals for the sessions. The resource usage control signalsrepresent a target pattern of use of the shared computing resource bythe sessions based on their respective activity values.

An enforcement operation is performed using the resource usage controlsignals to establish the target pattern of use of the shared resource bythe sessions.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, features and advantages will beapparent from the following description of particular embodiments of theinvention, as illustrated in the accompanying drawings in which likereference characters refer to the same parts throughout the differentviews.

FIG. 1 is a block diagram of a computer system employing activity-basedresource allocation among virtual-computing (V-C) sessions;

FIG. 2 is a schematic diagram showing V-C sessions extending between aclient and server, each session having multiple virtual channels;

FIG. 3 is a block diagram of a computing device from a hardwareperspective;

FIG. 4 is a functional block diagram of a set of software-implementedcomponents providing activity-based resource allocation;

FIG. 5 is a block diagram of an activity value calculation component;

FIG. 6 is a block diagram of a decision component including event-basedcorrection;

FIG. 7 is a flow diagram of a process of activity-based resourceallocation.

DETAILED DESCRIPTION Overview

For an end-user who is launching multiple virtual applications/desktopssessions on an end-point, allocate total bandwidth available on theendpoint device based on activity associated with each virtual sessionon this end-point. In this approach, sessions are identified that havegone into idle/inactive state, and bandwidth is shifted away from theseidle/inactive sessions and used to boost the bandwidth forin-focus/active/maximized sessions. This adaptive, intelligent approachcan improve the use of available bandwidth to improve system performancein scenarios where total available bandwidth is low and where theperformance of active sessions would have otherwise suffered.

Thus the following are characteristics of the disclosed technique:

a) Redistributing bandwidth (and other resources) available at theend-point/server/network device to ensure that inactive/idle virtualsessions get only a bare minimal and major chunk of available bandwidthis allocated to active virtual sessions.

b) Measuring weighted activity value for each virtual channel of eachsession and using them to influence the resource allocation (e.g.,bandwidth, compute, memory, etc.) on the endpoint between differentvirtual sessions and within individual sessions.

c) Using event-based correction factors to adjust or correct thedecision based on activity for resource allocation.

d) Learning and adapting activity value weights over a period of timebased on usage patterns of the user and manual user-feedback.

DESCRIPTION OF EMBODIMENTS

FIG. 1 shows a computer system including application servers 10 coupledto client devices 12 by a network 14. The application servers 10 areserver-type computers with hardware organization as generally known inthe art, and the client devices 12 are user-specific computing devicessuch as desktop computers, portable computers, etc. The system may alsoinclude an analytics server 16 as shown. One of the application servers10 and one client device 12 are shown in detail and described in detailbelow; in general the described organization and operation appliesequally to the other application servers 10 and client devices 12.

An application server 10 has a set of applications or “apps” (Apps) 18and virtual-computing (V-C) session server (VCSS) 20, and a clientdevice 12 has a local environment 22 and V-C session client (VCSC) 24.In operation, the client device 12 interacts with executing apps 18 vialogical channels referred to as “sessions” 26. Sessions are alsoreferred to as “virtual-computing sessions” or “V-C sessions” to reflecta virtual-computing aspect, i.e., that a user interacts with a remote,server-side application 18 as though it were executing locally, using awindow or desktop graphical paradigm for example. Generally, thesessions 26 are end-to-end logical entities as described further below,carried through the network 14 operating at lower levels (physicallayer, networking layer etc. as generally known). Examples and furtherdescription are provided below. In some embodiments the network 14 mayinclude a particular type of network device 28 that may operate at thelevel of the sessions 26 and thus be used for resource allocationenforcement, for example. An example of such a network device 28 is theCloudBridge device sold by Citrix Systems Inc.

The VCSS 20 and VCSC 24 establish and maintain the V-C sessions 26 andinterface them to the apps 18 and local environment 22 respectively. Asan illustrative example, one session 26 may be used by the client deviceto interact with a word-processing app 18, while another session 26 maybe used for some other application such as a database application, filetransfer, browser, etc. Within each session 26, sub-channels referred toas “virtual channels” or VCs are used to carry communications ofcorresponding components of the local environment 22 with the apps 18.Generally these components are input/output (I/O) devices such askeyboard, mouse, local storage device, printer, etc., as described morebelow.

As shown, the VCSC 24 may have communications connections 30, 32 to theNW device 28 and/or the VCSS 20 respectively. The connection 30 is usedwhen the NW device 28 is present and used for resource allocationenforcement, as described more below. The connection 32 may be used inconnection with enforcement as well as other functions, as alsodescribed more below.

FIG. 2 illustrates the structure of each V-C session 26 (26-1, 26-2,etc.) as including respective virtual channels VC. The VCs for session26-1 are shown as VC 1-1, VC 1-2, . . . , while those for session 26-2are shown as VC 2-1, VC 2-2, . . . , etc.

FIG. 3 shows an example configuration of a physical computer such as aserver 10 or client device 12 from a computer hardware perspective. Thehardware includes one or more processors 40, memory 42, and interfacecircuitry 44 interconnected by data interconnections 46 such as one ormore high-speed data buses. The interface circuitry 44 provides ahardware connection to the network 14 (FIG. 1) and perhaps otherexternal devices/connections (EXT DEVs). The processor(s) 40 withconnected memory 42 may also be referred to as “processing circuitry”herein. There may also be local storage 48 such as a local-attached diskdrive or Flash drive. In operation, the memory 42 stores data andinstructions of system software (e.g., operating system) and one or moreapplication programs which are executed by the processor(s) 40 to causethe hardware to function in a software-defined manner. Thus the computerhardware executing instructions of a V-C session client application, forexample, can be referred to as a V-C session client circuit component,and it will be understood that a collection of such circuits orcomponents can all be realized and interact with each other as one ormore sets of computer processing hardware executing different computerprograms as generally known in the art. Further, the applicationsoftware may be stored on a non-transitory computer-readable medium suchas an optical or magnetic disk, Flash memory or other non-volatilesemiconductor memory, etc., from which it is retrieved for execution bythe processing circuitry, as also generally known in the art.

FIG. 4 is a block diagram of functional components or modulesinteracting to provide the activity-based resource allocation describedherein. These are generally software-implemented components incorresponding computerized devices of the system, which may vary indifferent embodiments. Specifics are provided below.

An activity value (A-V) calculation component 50 and a prediction engine52 provide corresponding inputs to a decision engine 54, which in turnsupplies control signals to an enforcement component 56 as well asfeedback 58 to the analytics server 16. The A-V calculation component 50receives virtual-channel event data (VC Events) 60 used to trackactivity in the virtual channels VC, and the prediction engine 52similarly receives other event data (Other Events) 62 used to generateevent-based correction or adjustment of resource allocation decisions,as described more below. The analytics server 16 provides updatedweights 64 to the A-V calculation component 50 to refresh weight valuesstored therein. The analytics server 16 has the role of storing activitydata, feedback and deriving the mathematical expression with weightsusing that data. This server could be single/multiple with separatedand/or unified roles.

In one embodiment the A-V calculation component 50, prediction engine52, and decision engine 54 are all located within a client device 12,more specifically as part of VCSC 24 (FIG. 1). In alternativeembodiments, one or more of these components may be located within theVCSS 20, as described more below. As indicated, the enforcementcomponent 56 may be located within any one or more of the client device(Clt) 12, application server (Svr) 10, or network device (NW) 28. Otheraspects of the interfaces and interactions among the components aredescribed below.

FIG. 5 illustrates the A-V calculation component 50. It includes a storefor weights 70, a measured-influencer (M-I) calculator 72, and anactivity value (A-V) calculator 74. The M-I calculator 72 includes astate identifier 76 and an M-I mapper 78. The M-I calculator 72generates values referred to as “measured influencer” (M-I) values 80 tothe A-V calculator 74, which uses the M-I values 80 along with thestored weights 70 to generate per-session, per-VC activity values (A-Vs)82. The M-I values 80 are values representing activity states of thevarious VCs, while the A-Vs 82 are values representing weighted activitylevels of the VCs, provided to the decision engine 54 (FIG. 4) toinfluence operation of the enforcement component 56.

More specifically, the A-V calculator 74 uses the weights 70 and M-Ivalues 80 to arrive at the A-Vs 82. This calculation is performed firston a per-VC basis, and in one embodiment is as follows:

Activity value (AV_N)=Weight (A_N)×Measured Influencer (M_N),

where:

Activity value (AV_N) is the activity value for the Nth VC:

Weight (A_N) is an application-specific and virtual-channel specificweight value for the Nth VC, as described more below;

Measured Influencer (M_N) is a dynamic indicator of activity state ofthe Nth VC, also described more below.

Below is an example implementation of a table of weights 70. The VCs arenamed according to the respective type of I/O they are used for. Theper-VC weights are also application-specific as shown. Thus the weightfor the mouse channel, for example, is 0.7 for a Skype session but 0.6for a WMP session.

Application- specific Virtual virtual Windows channel channel MediaAutodesk/ Video File Windows (VC) bias/weight Skype player photoshopgames transfer word . . . 1. ThinWire  A1 0.2 0.8 Val Val Val Val 2.Mouse  A2 0.7 0.6 Val Val Val Val 3. Keyboard  A3 0.7 0.6 Val Val ValVal 4. Joystick  A4 0.7 0.6 Val Val Val Val 5. Microphone  A5 0.8 0.8Val Val Val Val 6. CDM  A6 0.2 0.2 Val Val Val Val 7. Printing  A7 0.20.5 Val Val Val Val 8. Generic  A8 0.8 0.5 Val Val Val Val USB 9.Scanner  A9 0.2 0.2 Val Val Val Val 10 Audio A10 0.8 0.8 Val Val Val Val11 Multimedia A11 0.8 0.8 Val Val Val Val 12 Other VC's A12 0.2 0.2 ValVal Val Val

Alternately, applications could be grouped into categories asappropriate and weights be defined on a category basis rather than on anindividual application basis. In one example, the following categoriesmight be used:

-   -   Bi-direction communication: Skype    -   Interactive: Word, gaming, Photoshop    -   Bulk: Scanning, printing, file transfers    -   Streaming: Media player

Below are table representations of the logic of the M-I calculator 72 inone embodiment, which includes state identification logic (stateidentifier 76) and M-I mapping (M-I mapper 78). One specific example isdiscussed to explain this logic, then several other tablerepresentations are provided for a full set of M-I values 80 as might beuseful in a given embodiment. It will be appreciated that this set oftables is specific to allocation of network bandwidth in particular. Ifthe technique is used for other types of resources, such as memory, CPU,etc., then in general the specifics of such tables may vary accordingly.

The example for detailed explanation is a Thinwire VC, which is used forremote display functionality (i.e., it carries the data and controlvalues by which the VCSS 20 and VCSC 24 collaborate to enable a desktop,application window, etc., generated at the application server 10 to bedisplayed in the local environment 22 of the client device 12).

Measured Influencer (M1) for Thinwire virtual channel:

State Value Notes Maximized 1 Minimized F(t) which goes from F(t) couldbe linear current value (either 1 or logarithmic or or 0.4) to 0 in 60sec. step function Windowed 0.4 Windowed 1 and focused

In the above representation, state identification 76 is represented bythe values in the “State” column as well as other information. For thislogic, the M-I calculator receives events 60 pertaining to userinteraction with the session window—events such as maximizing,minimizing, windowing, and gaining or losing focus (e.g., clicking inthe window to obtain focus, clicking elsewhere to lose focus). There mayalso be a timing component, which is indicated for the Minimized stateand described below. The state identifier 76 receives these events andtracks the current Thinwire state accordingly.

Based on the current state, the corresponding value in the Value columnis output as the M-I value 80 for the Thinwire VC. This is the mappingfunction of the M-I mapper 78—translating the current state to an M-Ivalue. For many states such as Maximized, the value is static. In somecases, there is also a timing component. This is indicated for theMinimized state, for which the output M-I value ramps down over a shortperiod after entering that state. Thus the M-I calculator 72 responds toa transition into Minimized by starting a timer, and the output value isramped down over the timer period according to some function shown asF(t). As indicated, in different examples F(t) is linear, logarithmic,or a step function.

Another way of describing the above logic is that for the Thinwire VC,there is at least one high activity state and at least one low activitystate, with the high activity state corresponding to active current useof the Thinwire VC, and the low activity state corresponding to currentnon-use (or perhaps low use) of the Thinwire VC. In this example, boththe Maximized state and the Windowed and Focused state are high-activitystates, and the Minimized state is a low-activity state. The Windowedstate (not focused) is an intermediate-activity state.

Below are shown several other table representations for logic of the M-Icalculator 72 for corresponding VCs. Again, these examples reflect usefor allocation of network bandwidth in particular; other specifics mayapply when other resource types are being managed. Almost all of theseinclude both a high activity state and a low-activity state; the Audiochannel is an exception in providing only one value for use at alltimes.

Measured Influencer (M2) for mouse virtual channel:

State Value Notes Mouse idle for 0 1 sec to 120 sec No mouse activityF(t) which goes from F(t) could be linear beyond 120 sec current valueto 0.5 in or logarithmic or 60 sec. step function

Measured Influencer (M3) for keyboard virtual channel:

State Value Notes No keyboard activity 1 for 0 to 120 see No keyboardactivity F(t) which goes from F(t) could be linear beyond 120 seccurrent value to 0.5 in or logarithmic or 60 sec. step function

Measured Influencer (M4) for joystick virtual channel:

State Value Notes No joystick activity 1 for 0 to 120 see No joystickactivity F(t) which goes from F(t) could be linear beyond 120 seccurrent value to 0.5 in or logarithmic or 60 sec. step function

Measured Influencer (M5) for microphone virtual channel:

State Value Notes Unmuted 1 Muted 0.2

Measured Influencer (M6) for CDM virtual channel:

State Value Notes Active 0.8 Inactive 0.1 Client drive 0 not mapped

Measured Influencer (M7) for printing virtual channel:

State Value Notes Print triggered 1 No printing 0

Measured Influencer (M8) for Generic USB virtual channel:

State Value Notes USB redirection 1 enabled (irrespective of activity)USB redirection 0 disabled

Measured Influencer (M9) for scanner virtual channel:

State Value Notes Scan triggered 1 No scan activity 0

Measured Influencer (M10) for audio virtual channel:

State Value Notes Irrespective 1 of the state

Measured Influencer (M11) for multimedia virtual channel:

State Value Notes Maximized 1 Minimized F(t) which goes from F(t) couldbe linear current value (either 1 or logarithmic or or 0.7) to 0 to 60sec. step function Windowed 0.7 Windowed and 1 focused

As described above, each activity value AV-N 82 for a given VC iscalculated as the product of a corresponding weight A_N andcorresponding M-I value M_N. The per-AC A-Vs 82 are provided to thedecision engine 54 for use in resource allocation.

FIG. 6 shows high-level structure of the decision engine 54 in oneembodiment. Its function is to distribute the use of the subjectresource (e.g., network bandwidth) across the sessions 26 based onactivity as represented by the A-Vs 82, as well as on other events 62 asrepresented by event-based correction factors (EVCFs) 90 generated bythe prediction engine 52 (FIG. 4). To this end, the decision engine 54includes summation logic (Sum) 92, session correction (S-Corr) logic 94,and VC correction (VC-Corr) logic 96. The session correction logic 94outputs session-level resource usage control signal (Res Cntl) 98, andthe VC correction logic 96 outputs VC-level resource usage controlsignal (Res Cntl) 100. In some embodiments, session-level resource usagecontrol (also referred to as “throttling”) may be sufficient, while inother embodiments there may be benefit to also distributing asession-level allocation among individual VCs of a session.

In one approach, bandwidth allocated for a session 20 should beproportional to the total activity of its constituent VCs, subject tocorrection based on other events. This general approach is reflected inFIG. 6. The sum logic 92 calculates a sum of the per-VC activity values82 across all VCs of a given session 20. This sum may be used raw or itmay be modified according to some function f, which may be linear,logarithmic or some other non-decreasing function. The sum (or functionthereof) is supplied to the session correction logic 94 along with theEVCFs 90. The session correction logic 94 may be realized such that itsimply passes through the sum value from summing logic 92 if noevent-based correction is necessary. In such a case, the resource usagecontrol signal 98 for a given session will be proportional to the sumvalue from the summing logic 92, and thus proportional to the weightedsum of M-I values 80 for all VCs of the session. In alternativeembodiments, some alternative mathematical expression may be used thatincorporates the weights derived from influencers. Event-basedcorrection can be done as a modification of a given sum value. Examplesare given below.

The VC correction logic 96 effects a distribution of resource usageacross individual VCs of a session, by generating the VC-level resourceusage control signals 100 accordingly. In one embodiment, the VCcorrection logic 96 also may be realized as a pass-through of the A-Vs82 for the corresponding VCs, subject to event-based correction. In thisexample, resource usage control signal 100-N for a given VC (VC-N) isproportional to AV_N, absent event-based correction.

For event-based correction, based on either user-triggered events orextraneous environment parameters, an EVCF 90 is calculated and used inthe decision of bandwidth allocation along with the activity value, inthe correction logics 94, 96. Examples of such correction scenarios areas follows:

1. Alt-tab or mouse hover-over on session tiles in the docking bar. Thisevent means that user is about to switch windows, so the correctionfactor should discount the activity in the resource allocation decisionbecause all activity values are soon going to change.

2. New session launch. As a new session launches, there might not bemuch activity associated with the new session, but the activity-basedallocation decision may be modified to prevent a new session from beingstarved of bandwidth because of low initial activity.

3. Accessibility settings of operating systems (e.g. Accessibilitysettings for visually-impaired users) may override any activity valuebased decisions.

4. Application-specific triggers such as end-of-meeting in Skype,Outlook reminder, etc. and usage-defined events/parameters such astime-of-the-day, GPS locations, docking/undocking etc. may be used toadjust the decision of bandwidth allocation.

The above description is directed to a client-based decision engine 54.Alternatively, the decision engine 54 may be server-based, i.e., locatedat the application server 10 for example. In this case, the client 12sends activity data to the server 10, and certain actions may beperformed to optimize resource usage based of the activity data. Serversinvolved in this way may perform various operations for managingresource usage such as the following:

1. Reducing the amount of data being sent to client

2. Increasing a timeout value for a session

3. Reducing the rendering rate (frames per second or “fps”) of video

4. Determining usage of licensed apps and prompting a user to close anapplication to optimize license usage

5. Informing an administrative user who may be able to adjust a user'snetwork environment (or other resource pool) to improve performance

It may be desirable also to maintain some minimum quota of resourcesallocated to minimized/out-of-focus sessions so that any time thecorresponding windows are maximized or brought back into focus,performance does not suffer unduly.

FIG. 7 illustrates key operation at a high level. The method dynamicallycontrols use of a shared computing resource (such as network bandwidth)by a set of virtual-computing sessions of a client computing device(e.g., 12), each session including a respective set of virtual channelsfor respective input/output (I/O) functions of the session.

At 110, state identification operations are performed onper-virtual-channel (per-VC) event data to identify respective activitystates of the virtual channels. The activity states include, for eachvirtual channel, a high activity state and a low activity state, withthe high activity state corresponding to active current use of therespective I/O function, and the low activity state corresponding tocurrent non-use of the respective I/O function. The activity states arerepresented by corresponding activity state data.

At 112, a resource allocation operation is performed using the activitystate data. In general, this includes (i) accumulating, for eachsession, activity state data for all virtual channels of the session toproduce a respective per-session activity value, and (ii) using theper-session activity values for the sessions to generate respectiveresource usage control signals for the sessions. The resource usagecontrol signals represent a target pattern of use of the sharedcomputing resource by the sessions based on their respective activityvalues.

At 114, an enforcement operation is performed using the resource usagecontrol signals to establish the target pattern of use of the sharedresource by the sessions. As mentioned, enforcement may also be viewedas adjusting or throttling use of the resource. Enforcement techniquescan include:

1. Using APIs provided by an operating system of the client device 12.

2. Using mechanisms at a networking layer of the VCSC 24.

3. Using the driver in the network stack of operating system such asNDIS drivers in

Windows.

Analytics

The analytics server 16 (FIG. 1) can provide both an initial set ofweights 70 as well as ongoing updated weights 64 (FIG. 5). The priorknowledge of the behavior of the applications 18 may be used as astarting point for assigning initial weights 70 to sessions. Theseweights, and perhaps the parameters for the Measured Influencer formulasas well, may be further refined based on feedback from the end-user andthe effectiveness of decisions to increase the resources allocated tomaximized or in-focus windows by reducing resources used by minimizedand out-of-focus windows. Calculations may be driven by data providedfrom multiple client devices 12, i.e., the learning aspect is influencedby operation across the entire system, not just for one client device 12or server 10.

User feedback could be manually entered ratings given by user as well aslearning of user behavior. For example, a user closing an applicationand re-launching may be interpreted as negative re-enforcement to adjustthe weights accordingly. Effectiveness of decisions can be measured bycomparing experience key performance indicators (KPIs). For example,frame-rate rendered on the client side may be compared to frame-rateprocessed at the server side, as well as the time to bridge the gapbetween client fps and server fps. For such a technique, the server-sideequivalent of the KPI may be used as a benchmark). In a cloudimplementation, feedback learned from across multiple customers can beused jointly to adjust global settings of weights and parameters for theMeasured Influencer formula.

Usage and application of the analytics could be based on per user/usergroup/application/application group/time of the day/industry.

User feedback may be obtained by measurement of activity value on theclient device 12. This builds on weights learned by the analytics server16, and further uses parameters from current usage (like sessionactivity) and environment (like effective network bandwidth seen by thedevice 12) to arrive at the activity value.

Allocation decisions may also be enforced based on administrativelyconfigured policies.

Alternatives

The description above is directed to allocation of network bandwidth onthe client side. Similar approaches can be used to control usage ofother limited resources on the client side, such as CPU usage, GPUusage, disk usage, etc.

A measure of activity value and client environment could be used indevices such as Netscaler and Director to do proactive maintenance ofthe environment.

Activity values could also be manually specified by an end-user. Forinstance, an end-user could explicitly mark a virtual session asinactive and another virtual session as active.

On the server side, by throttling the CPU usage based on activity value,further optimization on the common gateway protocol (CGP) could beachieved. This may optimize cost of the server by limiting usage of CPU,GPU, network, or other physical/virtual device.

Enforcing the learning and deriving could be any combination of serverswith dedicated roles/independent roles such as data store, analyticsserver, load balancer to achieve these roles.

A combination of on-premise and cloud solutions could be utilized aswell.

While various embodiments of the invention have been particularly shownand described, it will be understood by those skilled in the art thatvarious changes in form and details may be made therein withoutdeparting from the scope of the invention as defined by the appendedclaims.

What is claimed is:
 1. A method of dynamically controlling use of ashared computing resource by a set of virtual-computing sessions of aclient computing device, each session including a respective set ofvirtual channels for respective input/output functions of the session,comprising: performing state identification operations onper-virtual-channel event data to identify respective activity states ofthe virtual channels, the activity states including, for each virtualchannel, a high activity state and a low activity state, the highactivity state corresponding to active current use of the respectiveinput/output function, the low activity state corresponding to currentnon-use of the respective input/output function, the activity statesbeing represented by corresponding activity state data; performing aresource allocation operation using the activity state data, theresource allocation operation (i) accumulating, for each session,activity state data for all virtual channels of the session to produce arespective per-session activity value, and (ii) using the per-sessionactivity values for the sessions to generate respective resource usagecontrol signals for the sessions, the resource usage control signalsrepresenting a target pattern of use of the shared computing resource bythe sessions based on their respective activity values; and performingan enforcement operation using the resource usage control signals toestablish the target pattern of use of the shared resource by thesessions.
 2. The method of claim 1, further including: storingper-virtual-channel weight values representing relative contributions ofthe virtual channels to performance for each session; and applying theweight values to the activity state data in producing the per-sessionactivity values.
 3. The method of claim 2, wherein the stored weightsinclude respective sets of weights for respective distinct applicationtypes, and wherein applying the weights includes selecting one of thesets of weights based on a type of an application for which the sessionis being used.
 4. The method of claim 2, further including adapting theweights over time based on usage patterns of the user.
 5. The method ofclaim 1, wherein the resource usage control signals are generated usingthe per-session activity values and event-based correction factorsapplied to reflect additional events occurring at the client computingdevice.
 6. The method of claim 5, wherein the additional events includeone or more of a mouse hover over a window of an inactive session, or alaunch of a new session.
 7. The method of claim 1, wherein the sharedcomputing resource is network bandwidth.
 8. The method of claim 1,wherein the sessions are virtual-desktop or virtual-application sessionshaving windows generated at an application server being displayed in thelocal environment of the client computing device.
 9. The method of claim1, wherein the input/output functions include one or more of display,keyboard, mouse, or audio.
 10. The method of claim 1, wherein theresource allocation operation includes using the per-session activityvalues for the sessions to generate respective additional resource usagecontrol signals for the virtual channels, the additional resource usagecontrol signals representing a target pattern of use of the sharedcomputing resource by the virtual channels based on their respectiveper-session activity values.
 11. The method of claim 1, wherein theenforcement operation includes client-side throttling of usage of theshared computing resource performed at the client computing device. 12.The method of claim 11, wherein the client-side throttling is performedby a virtual-computing session component that maintains and utilizes thevirtual-computing sessions at the client computing device.
 13. Themethod of claim 1, wherein the virtual-computing sessions extend betweenthe client computing device and an application server, and wherein theenforcement operation includes server-side throttling of usage of theshared computing resource performed at the application server.
 14. Themethod of claim 1, wherein the virtual-computing sessions extend betweenthe client computing device and an application server through anintermediate network device, and wherein the enforcement operationincludes throttling of usage of the shared computing resource performedat the intermediate network device.
 15. A client computing deviceoperable to dynamically control use of a shared computing resource by aset of virtual-computing sessions, each session including a respectiveset of virtual channels for respective input/output functions of thesession, the client computing device including processing circuitrystoring and executing computer program instructions to perform a methodincluding: performing state identification operations onper-virtual-channel event data to identify respective activity states ofthe virtual channels, the activity states including, for each virtualchannel, a high activity state and a low activity state, the highactivity state corresponding to active current use of the respectiveinput/output function, the low activity state corresponding to currentnon-use of the respective input/output function, the activity statesbeing represented by corresponding activity state data; performing aresource allocation operation using the activity state data, theresource allocation operation (i) accumulating, for each session,activity state data for all virtual channels of the session to produce arespective per-session activity value, and (ii) using the per-sessionactivity values for the sessions to generate respective resource usagecontrol signals for the sessions, the resource usage control signalsrepresenting a target pattern of use of the shared computing resource bythe sessions based on their respective activity values; and performingan enforcement operation using the resource usage control signals toestablish the target pattern of use of the shared resource by thesessions.
 16. The client computing device of claim 15, wherein themethod performed by execution of the computer program instructionsfurther includes: storing per-virtual-channel weight values representingrelative contributions of the virtual channels to performance for eachsession; and applying the weight values to the activity state data inproducing the per-session activity values.
 17. The client computingdevice of claim 16, wherein the stored weights include respective setsof weights for respective distinct application types, and whereinapplying the weights includes selecting one of the sets of weights basedon a type of an application for which the session is being used.
 18. Theclient computing device of claim 15, wherein the resource usage controlsignals are generated using the per-session activity values andevent-based correction factors applied to reflect additional eventsoccurring at the client computing device.
 19. The client computingdevice of claim 15, wherein the shared computing resource is networkbandwidth.
 20. The client computing device of claim 15, wherein thesessions are virtual-desktop or virtual-application sessions havingwindows generated at an application server being displayed in the localenvironment of the client computing device.